In certain types of semiconductor devices, films of SiC are used for various purposes. Often the SiC film is applied over a layer of a glass. In such devices it is often desirable to pattern the SiC film and the glass layer beneath the SiC film by etching it. One reason for patterning the SiC film is to form holes in the film through which conductors of a metal film can extend. To provide for greater ease of forming the conductors in the etched holes in the SiC film, it is desirable to form the holes with tapered walls. Various techniques and materials have been developed for etching tapered holes in various materials used in the semiconductor field. However, heretofore there have been no readily and successful method of etching tapered holes in a film of SiC, and particularly, also through a glass layer beneath the SiC film.